Clarifying documentation on including a top-level @TestConfiguration class in a test #30513
Description
A test configuration annotated with @TestConfiguration does not override a bean, if it is defined as a separate class. Only using @TesConfiguration on an inner class works in this case.
Not working:
@TestConfiguration public class ExternalTestConfig { @Bean public MyBean myBean() { return Mockito.mock(MyBean.class); } }@SpringBootTest(properties = "spring.main.allow-bean-definition-overriding=true") @Import(ExternalTestConfig.class) public class ExternalTestConfigApplicationTest { @Autowired private MyBean myBeanMock; @Test void contextLoads() { // test fails, if myBeanMock is not a mock Mockito.verifyNoInteractions(myBeanMock); } }Working:
@SpringBootTest(properties = "spring.main.allow-bean-definition-overriding=true") class InnerClassTestConfigApplicationTest { @Autowired private MyBean myBeanMock; @Test void contextLoads() { // test fails, if myBeanMock is not a mock Mockito.verifyNoInteractions(myBeanMock); } @TestConfiguration public static class TestConfig{ @Bean public MyBean myBean() { return Mockito.mock(MyBean.class); } } }My example uses spring boot 2.6.6, code can be found here: https://github.com/spring-boot-demos/demo-testing-bean-overriding
I read several blogs and articles and found some other examples, which do not work, e.g. this blog with example code which is very similar to my example code.
In my understanding, the behaviour of a class annotated with @TestConfiguration should be the same, no matter if defined as inner or separate class.